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FAQs: NIOSH-Interactive RadioEpidemiological Program (NIOSH-IREP)

To determine probability of causation for a cancer claim under The Act, DOL uses a computer software application NIOSH has developed in collaboration with the National Cancer Institute, called NIOSH-IREP. This computer software is a science-based tool that allows DOL to determine the probability a cancer was caused by a person’s radiation dose from nuclear weapons production work. The actual outcome of a claim depends on a number of important factors such as the dose estimates of past exposures and the type of cancer that has been diagnosed. DCAS is responsible for maintaining and updating this software and the scientific elements (cancer risk models) that it uses.

To find answers to your questions about NIOSH-IREP, click any one of the questions listed below to view its answer.

NIOSH-Interactive RadioEpidemiological Program (NIOSH-IREP)

What is IREP?

The Interactive RadioEpidemiological Program (IREP) is a web-based, interactive computer code that is used to estimate the probability that a given cancer in an individual was the result of a person's occupational exposure to ionizing radiation.

When was IREP developed?

IREP was developed in 2002 by a Working Group of the National Cancer Institute (NCI) and Centers for Disease Control and Prevention (CDC).

Why was IREP developed?

IREP was developed to provide an update of the 1985 National Institutes of Health (NIH) Radioepidemiological Tables. The 1985 tables were developed from analyses of cancer mortality risk among the Japanese atomic bomb survivor cohort. These tables allow computation of the probability of causation for various cancers associated with a defined exposure to radiation, after accounting for factors such as age at exposure, age at diagnosis, and time since exposure.

A defining characteristic of IREP is that it accounts for uncertainties in estimating cancer risks due to exposure to ionizing radiation and in evaluating causation of a given cancer in an individual.

NIOSH-IREP is a customized version of IREP, created and maintained by NIOSH for use by DOL in adjudicating claims under The Act. NIOSH-IREP was originally developed to reflect the radiation exposure and disease experiences of employees covered under The Act.

Has the NIOSH-IREP code ever been verified to ensure that it operates according to its intended use?

Yes, a formal verification effort was undertaken and the report, Verification of the NIOSH-IREP Computer Code Version 5.5.3 Report, presents the results of this effort. It was organized to ensure that the most current version of NIOSH-IREP software (version 5.5.3) calculates risk and probability of causation (PC) according to the methodology agreed upon by NCI and NIOSH. This verification process was performed by individuals of SENES Oak Ridge, Inc., who were not involved in the initial development of the code. It is important to note that this effort has not attempted to "validate" or question the models and procedures developed by NCI and NIOSH; this effort "verifies" that each part of the NIOSH-IREP code operates according to its intended use described in its technical documentation.

Where can I find a copy of the Verification of the NIOSH-IREP Computer Code Version 5.5.3 Report?

What is a cancer risk model?

A cancer risk model is a mathematical relationship that expresses the risk of developing a specific cancer for a given dose of ionizing radiation and is used to estimate the probability of causation (PC).

What are the cancer risk models based on?

Risk models are based mainly on the observed cancer incidence from the Japanese atomic-bomb survivor study, but also from other epidemiological studies. The risk values in the models are adjusted for the U.S. population, based on U.S. cancer rates. Appropriate adjustments of the risk values are also made for low dose and low dose-rate exposure situations.

Who maintains/updates NIOSH-IREP?

NIOSH is responsible for maintaining and updating this software and the scientific elements (cancer risk models) that it uses.

Is NIOSH-IREP claimant favorable?

As applied, NIOSH-IREP is claimant favorable because it uses the upper 99-percent credibility limit to determine whether the cancers of employees are at least as likely as not caused by their occupational radiation doses.

What cancer risk models are included in NIOSH-IREP?

Cancer Risk Models Included in NIOSH-IREP

Oral cavity and pharynx (140-149)

Esophagus (150)

Stomach (151)

Colon (153)

Rectum (154)

All digestive (150-159)

Liver (155.0)

Gallbladder (155.1, 156)

Pancreas (157)

Lung (162)

Other respiratory (160, 161, 163-165)

Bone (170)

Connective tissue (171)

Malignant melanoma (172)

Non-melanoma skin-Basal Cell (173)

Non-melanoma skin-Squamous Cell (173)

Breast (174-175)

Ovary (183)

Female Genitalia, excl. ovary (179-182, 184)

All Male Genitalia (185-187)

Bladder (188)

Urinary organs, excluding bladder (189)

Eye (190)

Nervous system (191-192)

Thyroid (193)

Other endocrine glands (194)

Other and ill-defined sites (195)

Lymphoma & multiple myeloma (200-203)

Leukemia, excl. CLL (204-208, excl. 204.1)

Acute Lymphocytic Leukemia (204.0)

Acute Myeloid Leukemia (205.0)

Chronic Myeloid Leukemia (205.1)

Would NIOSH ever need to run more than one cancer risk model to determine the PC?

Yes, some types of cancers require running more than one IREP model to see which one produces the highest probability of causation.